Electric cut-out



Jan. 31, 1933.

E. O. SCHWEITZER ELECTRIC CUT-OUT Original Filed June 12. 1930 wmf/31%@ Patented Jan. 31, 1933 PATENT OFFICE EDMUND O. SCHWEITZER, OF NORTHBROOK, ILLINOIS ELECTRIC CUT-OUT Continuation of application Serial No.

vThis application is a continuation of in pending application, Seria-1 No. 460,582, filed June 12, 1930. The above application refers to fused cut-outs wherein a fuse is mounted 52 in a chamber containing oil or other insulating liquid, for interrupting a circuit under certain conditions and a switch is mounted in the same chamber for interrupting the same circuit under other conditions. 10 It is an objectof the present invention to provide an improved casing structure employing an improved bushing structure for extending a conductor thereinto.

The attainment of the above and further objects of the present invention will be apparent from the following specification taken in conjunction with the accompanying drawing forming a. part thereof.

In the drawing:

Figure 1 is a plan view of my improved cut-out, the cover being removed;

Figure 2 is a view in partial section takenV along the line 2-2 of'Figure `1, certainof the parts being shown in section and others being shown in elevation;

Figure 3 is a fragmetary sectional'view taken along the line 3-3 of Figure 2 and looking in the direction of the arrows;

Figure4 is a view similar to Figure 3 and showing an alternate form of construction;

and

Figure 5 is a fragmentary sectional view of al modified form of bushing construction.

Referring now more particularly to the 5 drawing, the cut-out comprises an open top casing 1 which is adapted to receive the various operatingparts and which is filled withinsulating oil or other insulating liquid to alevel as indicated by the line 2. The 49 casing is provided with a novel bushing structure for lea-ding the line conductors into the casing. Each bushing includes a bushing shield comprising a nipple and insulating sleeve 5 through which the conductor 6 extends. The nipple is forced through a suitable opening in the casing 1, said nipple making a press fit within the opening. The insulating sleeve 5 having the conductor 6 fitting tightly therein is itself pressed into the nipple 4, said sleeve being pressed upward 460,582, filed .Tune 12, 1930. This application filed September 1l,

1931. Serial No. 562,243.

y into the nipple from the bottom side thereof.

The insulator 5 is provided with a fi-ange having anl upper tapered surface 7 that seats against a corresponding tapered surface at the inner bottom side of the nipple and limits the extent of inward movement of the insulatingsleeve 5 Within the casing 1. Since the various parts are press fitted within one another leakage of insulating liquid from within the casing 1 is prevented.

The conductor 6 has a portion 8 extending beyond the insulating sleeve 5, constituting means for establishingxa connection with a suitable conductor for extending a circuitA through the cut-out. Prior to the making of the connection with the incoming line conductor, a guarding sleeve 10 and a clamping nut 11 are slipped over the end of the conductor and, upon the completion of the electrical connections with portion 8 of the conductor 6 the guarding sleeve is brought up to bear against the fiange 6 of the insulator 5, said sleeve and said flange being both provided with cooperating tapered portions forming a conical seat 12. The clamping nut 11 is then threaded to the bottom of the nipple 4 and, at the shoulder 13, it clamps the guarding sleeve 10 and the insulator 75 against the nipple 4 thus effectively securing both of those members against outward withdrawal. A contact terminal 15 having a pair of projecting ears 16 is clamped to the end of the conductor 6 within the casing 1 by means of a suitable screw or bolt 17. The Contact 15 is tightly clamped around the conductor 6 and it rests against the insulating sleeve 5 thereby preventing the Withdrawal of the conductor 6 through the sleeve and out of the casing.

The top of the casing 1 is provided with an inturned circular rim or flange 18 upon which is adapted to be seated a circular disc 19 from which is suspended the various operating parts, and a cover 20. A pad 21, of felt or the like, is interposed between the cover 20 and the fiange 18 in order to provide an effective seal t0 prevent the entrance of moisture or other foreign material into the casing. The cover 20 is bolted to the 100 flange 18 by means of six bolts indicated atl 22 i extend through openings in the block 2li/on opposite sides of the center thereof Yand are looked thereto by lower nuts 41 and an upper washer42 and an upper `nut 43. The studs 4U are made of copper or other metal .offhigh electric conductivity. Laminated spring contacts 4:5 are mounted'between-the llock nut 43 andthe `,washer 42 andare held infirm electrical contact with the-stud `by meansV of the nut-48. A pivot member 48'is welded or 219"otherwisesecured Ato the 'left hand .contact spring45-and asimilar-member 49 is similarly @secured to 'the -Iight 4'hand .contact spring 45.. The member L8 =is.:piv.oted between Atwo arms fof a ,linklby nieansfota l:pin 52 which 257 extends through-a acircular hole .in :the arms offthemember5`1and througha similar hole in the member 48, said member 48 being lro-V tatable with respect to the arms v'of the link 51. The memfber 49 is similarly pivoted between the two arms of a link35 simil-ar in construction to the link 5-1. 'Ihe two links 51- and ,55 rare pivotally connected together by means of two pins 56'and 57 located at the d opposite sides of 4the sets of Vlinks,said pins extending through Vholes in the adjacent ends of the links andfscrewing into a nut 58 that lies between lthe two arms of the .flink 51. The nut '58 comprises merely :a square block which tits between the two arms of the link 19 land which is provided witha central opening Aiorreceivingan operating shaft in a mannerl to -be more fully set forth 'aslthe description proceeds. The links 51 and 55 are made of suitableelectrical insulating material soa-s 45 not to constitute a short circuit between the contact springs *45' and they .constitute a toggle for forcing the contacting ends of the springs i5 into engagement with the Contact 15 mounted within kthe casing l .as previous- 53 ly described.V The links 51 and 55constitute a toggle which is on dead center when the switch is in its closed position., -as illustrated, and which is `forced tothe openposition by the action of the spring pressure of the Contacts 45 when the toggle is knuckled slightly upward.

An actuating or tripping rod 59 is screw threaded through an internally threaded opening 'in the member 58, being locked in i? place by means of va lock nut 60.V The lock nut 60 may be omitted if desired; It is to be noted that'the block y'58 is pivoted between the links so that Vit may remain horizontal when the toggle breaks.

A block vof insulating material issuspended from the studs 40, and a fuse link material. The studs lO-lO thread into these i plates Yand the compression block 65 rests upon them. The screw members 66 and 67 thread into these blocks to secure the fuse thereto 4and to'establishan `electric circuit @between the studs 40-40 through the fuse.

The block 65 has a cylindrical bore 75 formed therein lat its center .and extending upwardly from the 'bottom Vfor Aa distance :approximately half way .through theliblock. Six small holes indicated in general'at 7 6 fare drilled through theiremaining vportion of the rblock'65 above theend'ofthe bore 75. .An expansible member or chamber 78 which anay be ot .any suitable :construction and which in `the modification herein .shown comprises an expansible bellows, .is mounted V,upon `the' block :6,5 A.and is provided Vwith a projecting st-ud 8O which :projects .through a central opening in the vblock 65 .and extends downwardlyiinto physical-contact with the fuse 66.

The projecting stud V8O is made of :suitable heat conducting `material so as l'to conduct heat lfrom the fuse `to the material within kthe bellows 78. Y

A compression block 86 of suitable vinsulating material ,is lbolted or :otherwise "suitably secured to the ,bottom of the block 65 and :con-- stitutes a cover forthe fuse. The block 86 is provided with v depressions :into which 'thescrews 67 seat and is secured to the block'65 by means of two screws that are located midway nbetween fthe screws 67-67 and on opposite sides of a line joiningthose screws and pass into tapped holes in 'the block 65. The

compressionblock 86 is provided witha rec` tangular slot 88 for permitting the voil or other insulating liquid within the casing 1 to circulate around the fuse. A cylindrical sleeve 89 ofsuitableheat insulating-and electrical insulating material extends ybetween the blocks '25 and 65 and'surrounds vthe bellows, being spaced therefrom. The purpose of this sleeve is to limit the extent of circulation of the liquid within the casing 1 around the bellows. Thus lthe oil that is heated by the Vruse rises rinto the space between the tbe'llows and the sleeve and serves to eii'ectively heat the bellows. In addition the sleeve prevents the accidental contact between the bellows and the studs ,tO-40. It is within the sleeve if desired.

The bottom of the actuating or tripping rod 59 extends into a short cylindrical bore ina fitting 90 onthetop'ofthe bellows 78. The bottom of the rod 59 `terminates asshort purview of the present invention to omit the distance from the end of the bore in the fitting 90 whereby a limited amount of expansion of the bellows is permitted without producing any effect upon the rod 59. Upon further expansion of the bellows the rod 59 is moved upwardly, moving the knuckle of the toggle links 51-55 upwardly to break the toggle and permit the spring contacts 45 to force the switch to snap open.

An explanation will now be given of the manner of operation of my improved circuit interrupter. When the switch is in the closed position a circuit extends from the conductor 6, through the terminal contact 15, through the end 91 of the right hand spring contact 45, the right hand stud 40, the fuse 66 and the left hand stud 40, thence by way of the left hand spring contact 45 and the left hand terminal contact 15 through the conductor within the left hand bushing. The fuse 66 is purposely made of a capaclty greatly vin excess of the continuous current capacity of the circuit in which it is connected. Should the load current exceed the rated amount for which the fuse is designed, the fuse will commence to overheat and should the overload continue for an extended period of time the liquid adjacent the fuse will be appreciably heated. The bulk of the heated liquid will rise and will act to heat the liquid within the bellows 78. In addition, the stud 80 which is in close proximity to the fuse link and therefore in the region of the hottest liquid, will conduct heat to the liquid within the bellows. The bellows may be filled with oil of the same kind as is contained within the casing 1, or it may be filled with any other liquid having an appreciable coeiiicient of expansion at the temperatures used. Carbon tetra-choride, ether, or the like may be used. Upon being heated, the liquid within the bellows will expand thereby expanding the bellows. It is to be understood that the liquid within the entire casing 1 will also be heated but due to the construction of the cut-out, as shown, the temperature gradient will be such that the liquid in the region of the bellows will be heated sooner and to a higher temperature than will be the rest of the body of liquid in the casing 1. Upon the expansion of theliquid within the bellows the top of the bellows comes into engagement with the bottom of the actuating or tripping rod 59. Upon further expansion of the bellows the rod 59 is moved upwardly thereby moving the knuckle of the toggle 51-55 upwardly and out of dead center. The spring contact members 45 being under stress now act through the members 48 and 49 to force the knuckle of the toggle upwards, the members 48 and 49 about the respective links 51 and 55 at the pins 52. The ends 91 of the contact brushes 45 thereby move out of engagement with the terminals 15, thus breaking the circuit between the conductor 6 and the corresponding conductor in the left hand terminal bushing. It is to be noted that the tripping of the switch is dependent upon the expansion of the liquid within the bellows 79, which expansion is not dependent upon the existence of a temperature difference between the liquid within the bellows and that outside of the bellows. Thus, even if there should be a circulation of the liquid outside of the bellows, that is the liquid within the casing 1, the switch would nevertheless be tripped upon the occurrence of a continuing overload. When the switch trips, the plunger 59 is moved upwardly, said plunger extending through an openin in the top 20 of casing and into a sleeve 92 w ich is closed at its outermost end is threaded into the cover member 20.

To reset the switch, the cap portion 92 is unscrewed and the operating rod or plunger 59 is pushed downwardly. This forces the contact springs 45 back into engagement with the contact 15 thereby assuming the position shown in full lines in Figure 1. In order to limit the extent of downward motion of the knuckle of the toggle comprising the links 51-55, one of the links 55 is extended beyond the knuckle as indicated at 55 and is provided with an extended portion 55a which engages the pin 52 when the links 55 and 51 reach a position of alignment. For this purpose the pin 52 is extended beyond the link 5l at one end thereof. It is thus merely necessary to depress the operating rod 59 downwardlyas far as it will go in order to bring the switch into its full closed position.

From the description thus far given it is apparent that the distance between the bottom of the tripping rod 49 and the bellows 7 8 when the switch is closed will determine the extent of permissible expansion of the bellows without operating the switch. In order to vary the extent of permissible operation of the bellows the rod 59 may be adjusted lengthwise of the member 58 to bring the bottom of the rod closer to or further away from the bellows. This may be accomplished by loosening the lock nut 60, if such a nut is provided, and then rotating the rod 50 to lower it. The disc 19 is calibrated as indicated at 95 and a pointer 96 is mounted upon the operatin rod 59 so that upon turning of the operating rod to advance the rod towards or away from the bellows the pointer 96 moves across the calibrated scale 95 to indicate the extent of permissible operation of the bellows. The pointer 96 is preferably mounted upon the rod 59 so as to be freely slidable with respect thereto to a limited extent but it is nonrotatable with respect to the rod 59. This may be accomplished by making the rod 59 square at its end. This willkpermit the free rising of the operating rod 59 when the switch is tripped. When the operating rod rises due to the tripping of the switch the pointer 96 may be held against rising by engagement thereof with the cover 20. It is, of course, e

to be understood that any other desirable arrangement may be provided for indicating the extent of turning of the rod 59 and thereby indicating the extent to which the rod has been advanced towards or withdrawn from the bellows. As an alternative arrangement the central opening in the block member 58 need not be internally threaded. The rod 59 1Q. extends freely through the opening and is heldin place by means of a pair of lock nuts l60--60- as shown in Figure Ll. In such an arrangement it is necessary to withdraw the operating mechanism from within the casing 1 in order to adjust the rod 59 to vary the extent of permissible operation of the bellows 78.

Should an exceedingly-heavy overload such as a short circuit or-the like occur upon a S line which is being protected by my improved cut-out then the circuit will be interrupted instantly by the blowing of the fuse.

In Figure 5 I have showna modified form of bushing structure applicable to a cut-out j; such as shown in Figures 1 and 2. In this ligure I indicate a fragmentary portion of the tank 1 and a nipple 4l press fitted into an opening therein in the same manner as is nipple 4 of the cut-out illustrated in Figure T 2. AThe nipple lis however made of insulating material. A plug provided with an iron rimmed cap. 101 is screw threadedon the outside ofthe nipple 4. The plug 100 may be made of suitable insulating material, 3551 such as a phenol condensation product or the like molded to the cap 101. The plug is of a hollow cup-shaped configuration on the inside and is provided with an opening through which the conductorG may be extended. The 3401 conductor 6 makes a press fit through the hole in the plug 100 so as to be liquid tight. The cup-shaped opening in the plugis filled with wads or tufts of paper which are slightly moistened with water. The wads or tufts f1-5i of paper 104 arethen compressed by means Y of al disk 105 of suitable insulation, such as a phenol condensation product, which threads on the inside of the nipple 4. The disk 105 makes a close it with the conductor 6 thereby 5u certainly maintaining the conductor in its aligned position through the plug 100. The side of the conductor 6 that extends within the casing of the cut-out is provided with a switch contact as illustrated in Figure?l and Q53; the opposite end extends from the nipple and is adapted to have connected thereto a suitable lead in conductor in any desired manner.

I have found that a very slight amount of moisture in the wads of paper 104 will effec- CQ tively prevent creepage of oil between the disk 105 and the conductor 6 or between the disk and the inner wall of the nipple l. The moisture appears to act as a repellent or support for any film of oil that-may commence to pass through the almost microscopic spaces that may be present. -The supported lm of oil therefore acts as a plug to prevent the outward passage ofadditional oil. A very minute quantity of moisture in the paperl vention is not limited to the precise construction herein shown, but is capable of modification within the spirit and scope of the appended claims. What I consider new and desire to secure by Letters Patent is:

1. In an electric switch comprising a closed container adapted to be filledwith liquid and having a hole formed therein for receiving a bushing Y structure, a sleeve extending through the hole and making a tight fit therewith, a tubular insulator extending into the container through said sleeve and having a flange abutting against the outside of the sleeve, said tube constituting a closure for the sleeve, a conductor extending outwardly from the container through the tube of insulation, switch contact means supported on l the portion ofthe conductor within thecontainer and limiting the extent of withdrawal of the conductor through the tube of insulation, and clamping means for clamping the flange of the tube of insulation against the outside of the sleeve. Y Y

2. A bushingv structure comprising a tube of insulation, a conductor fitting tightly within the tube and extending beyond the end thereof, a switch contact secured to the extended end of the conductor and abutting against the tube for preventing the withdrawal of the extended end of the conductor through the tube, a shell member through which the insulating tube extends, said tube fitting tightly within the shell member, a iange formed on said tube and spaced from the end thereof on the side of the shell opposite the terminal, said flange having tapered sides, and means for clamping the tapered sides of the flange against the shell. n

3. An oil filled switch casing of smaller cross section "at the lower end than at the upper end, a portion ofthe casing affording a tapering connection between the larger and smaller ends, a nipple extending outwardly from said tapered portion, an insulating sleeve press tted into the nipple and having a conductor extending therethrough into the casing, a guarding sleeve surrounding the outwardly extending end of the conductor and having a sliding telescoping engagement with' lthe insulator, common clamping means for clamping both the insulating sleeve and the guard to the nipple, a contact secured to llO tor and retaining the conductor against retraction from the sleeve, and switching means within the casing movable into and out of electrical engagement with the contact.

4. An electrical device including an oil containing casing, means extending through the casing, and means comprising wads of moistened paper clamped about the rst named means for producing an oil tight seal.

5. An electrical device including an oil containin casing, an insulating nipple extending extending through the nipple into the casing, a plug carried by the nipple and making a tight fit with the conductor and including a moisture containing substance compressed about the conductor for producing an oil tight seal.

In witness whereof, I hereunto subscribe my name this 9 day of Se tember, 1931.

EDMUND O. CHWEITZER.

erefrom, an electrical conductor 

